JPS63253995A - Voice mailing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a voice mail device that converts an analog voice signal into a digital voice signal and records the signal.

2. Description of the Related Art Conventionally, in this type of voice mail device, the method shown in FIG.
As shown in a), the analog audio signal recorded by the microphone 1 is sampled by the A/D conversion circuit 2 using a clock of a predetermined sampling frequency, converted into a digital signal such as a PCM code, and stored in the memory 3. be done.

On the other hand, the digital signal stored in the memory 3 is shown in FIG.
As shown in b), the D/A conversion circuit 4 converts the signal into an analog audio signal, and the speaker 5 reproduces the audio signal.

Problems to be Solved by the Invention However, in the conventional voice mail device described above, in order to store an uncompressed digital signal in the memory 3, a large capacity or large capacity is required to record and play back a long voice signal. There is a problem that the memory 3 is required.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a voice mail device that can record voice signals over a long period of time with a small capacity or small memory.

Means for Solving the Problems In order to solve the above problems, the present invention converts a digital signal into a frequency domain signal, and converts a plurality of numbered representative patterns of the frequency domain signal and the frequency domain signal. The present invention is characterized in that a representative pattern with minimum distortion is calculated by comparing signals, and the number of the representative pattern is encoded.

According to the above-described configuration, the present invention compresses the audio signal by encoding the number of the representative pattern of the signal in the frequency domain, so that it is possible to record a long audio signal with a small capacity or a small memory.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic block diagram showing an embodiment of the poismail device according to the present invention, FIG. 2 is a detailed block diagram of the encoder of FIG. 1, and FIG. 3 is a main signal of the main signal of FIG. waveform diagram, 4th
The figure is an explanatory diagram of main signals of the encoder of FIG. 2.

In FIG. 1, FIG. 1(i) shows the recording system of the Poismail device, and FIG. 1(b) shows the reproduction system of the Poismail device.

In FIG. 1(a), 11 is a microphone that converts audio into an analog audio signal; 12 is a microphone that converts audio into an analog audio signal;
A/D conversion circuit that converts into digital signals such as M code,
13 is an FFT (fast Fourier transform:
fastFourier transform) circuit.

14 is an encoder that compares the frequency domain signal transformed by the FFT circuit 13 with a representative pattern previously stored in the memory 16, extracts the representative pattern with the least distortion, and encodes its number; , a memory in which data encoded by the encoder 14 is stored.

Here, if the number of samples of the frequency domain signal in one section divided by the FFT circuit 13 is M, then the memory 16 (U) stores in advance a plurality of N representative patterns Yj (j=1.2
,...,N) Yj=(YJl, Y3z,..., YJpa) is stored.

In FIG. 2, 211 to 21N are respectively distortion calculation units that calculate the distortion Sj of the frequency domain signal X from the FFT circuit 13 and the representative pattern Yj stored in the memory 16, as described later, and 22 is a distortion calculation unit. This is an encoding unit that compares the distortion SJ in each of the representative patterns Y from the units 211 to 21N, extracts the representative pattern YJ that has the minimum value, and encodes its number j.

Returning to FIG. 1(b); C 17 reads the encoded data from the memory 15 and converts the encoded data into a frequency domain signal using a representative pattern stored in advance in the memory 16;
A decoder for decoding, 18 is an inverse FFT circuit that converts the frequency domain signal from the decoder 17 into a time domain signal, 19 is a converter for converting the signal from the inverse FF'r circuit 18 into an analog audio signal. The D/A conversion circuit 20 is a speaker that reproduces the analog audio signal from the D/A conversion circuit 19 into audio.

Next, the operation of the embodiment according to the above configuration will be explained with reference to FIGS. 3 and 4.

First, when an analog audio signal as shown in FIG. 3(a) is input to the microphone 11, it is converted into a digital signal by the A/D conversion circuit 12, and further converted into a digital signal by the FFT circuit 13 as shown in FIG. 3(b). a predetermined time interval (e.g.
Figure 3 (C)
Each signal is converted to a frequency domain signal as shown in .

Here, as shown in FIG. 4(a), the frequency domain signal X is X=(X1%X2,..., Calculate Sj.

The encoding unit 22 receives the distortion sJ from the distortion calculation units 211 to 21N.
The representative pattern Yj with the minimum S' is extracted, and the number ' is encoded by binary coding, for example, and stored in the memory 15.
Store in.

Therefore, according to the above embodiment, in order to compress the sampling sequence of the digital signal, encode the representative pattern number, and store it in the memory 15, long-term audio data is stored in the memory 15 with a small capacity or a small number. can do.

On the other hand, when reproducing the audio data stored in the memory 15, the decoder 17 decodes the representative pattern Yj corresponding to the number j, and the decoded representative pattern Yj is converted into the time domain by the inverse FFT circuit 8. It is converted into a signal and output continuously for each divided section.

This signal is converted into an analog audio signal by the D/A conversion circuit 19, and the audio (-) is reproduced by the speaker 20.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention converts a digital signal into a frequency domain signal and compares the frequency domain signal with a plurality of representative patterns of frequency domain signals assigned numbers in advance. Since the representative pattern with the minimum difference is calculated and the number of the representative pattern is encoded, the audio signal can be compressed.
It is possible to record audio signals for a long time with a small capacity or small memory.

[Brief explanation of drawings]

1 is a schematic block diagram showing an embodiment of the voice mail device according to the present invention, FIG. 2 is a detailed block diagram of the encoder of FIG. 1, and FIG. 3 is a main block diagram of the encoder of FIG. FIG. 4 is an explanatory diagram of the main signals of the encoder of FIG. 2, and FIG. 5 is a block diagram showing a conventional voice mail device. 11...Microphone, 12...A/D conversion circuit, 1
3...FFT circuit, 14... Encoder, 15, 16
...Memory, 17...Decoder, 18...Inverse FF
T circuit, 19... D/A conversion circuit, 20... speaker. Name of agent: Patent attorney Toshio Nakao (1st person)
[Figure 2 Figure 3 OJJ Chari (Moan%L Cb) ηL Figure 5 (b)

Claims (1)

[Claims] A/D conversion means for converting an analog audio signal into a digital signal; FFT means for converting the digital signal from the A/D conversion means into a frequency domain signal; and a plurality of numbered frequency domain signals. storage means in which a representative pattern is stored in advance, and means for calculating a representative pattern with minimum distortion by comparing the frequency domain signal from the FFT means and the representative pattern, and encoding the number of the representative pattern. and means for storing said encoded data.